a) Field of the Invention
The present invention relates to an automatic particle pattern judging method, which is for judging particle patterns formed in bottom surfaces of reaction vessels by an immunological agglutination reaction. Such judgement is conducted for a clinical test purpose. In the method according to the invention, the particle patterns are measured in an optical manner and then it is automatically judged whether the particle patterns are agglutinated or not.
b) Prior Art Statement
An immunological agglutination reaction is used for judging a type of composition of blood, such as erythrocyte type and leukocyte type, for analyzing a shape or a kind of platelet or lymphocyte and for detecting a presence of antibody, antigen, specific protein and/or virus in a sample liquid, such as blood, humor and urea. The immunological agglutination analysis is conducted such that the sample is mixed with reagent such as hemocyte particles, rates particles and carbon particles to introduce an agglutination reaction; and the particle pattern formed in the reaction vessel by the agglutination reaction is measured to judge whether the pattern is agglutinated or not. It is possible to judge visually whether the particle pattern is agglutinated or not, but there are some problems in objectivity and in measuring accuracy. Therefore, an automatic particle pattern judging method is widely used. By the method, it is possible to judge the particle pattern automatically with a high detecting accuracy and thus a lot of specimens can be processed.
Such automatic particle pattern judging method is suggested, for instance, in Japanese Preliminarily Laid Open Patent Publication No. 58-105065, in which the judgement of the particle pattern is conducted by using a parameter of a ratio between a light intensity of a center portion of the particle pattern to be tested and that of a peripheral portion thereof; and it is also suggested in Japanese Preliminarily Laid Open Patent Publication No. 61-215948, in which the judgement is conducted such that an area of a portion where the particles are gathered to form an agglutination pattern or a non-agglutination pattern is obtained by using an image picking up device and then whether the particle pattern is agglutinated or not is judged by comparing the area with a given threshold value.
In such automatic particle pattern judging method, however, there is a problem that blood cell particles to be tested sometimes could not be delivered exactly into the reaction vessel in accordance with a given amount. The following are considered as causes of such misdelivery: sexual difference or age difference in patients; a condition of centrifugal separation, which is conducted for separating the sample into plasma and blood cell; a variation of sample caused by a long time delay since the sample is picked up from patients; an amount or a kind of anticoagulant which has been mixed into the sample; and a buffy coat included in the sample. Under such situations, the judgement of the agglutination pattern cannot be conducted correctly. For instance, the amount of the blood cell particles to be tested delivered into the reaction vessel is so small that the particle pattern formed in the reaction vessel is sometimes judged as a negative pattern nevertheless the pattern is actually pseudopositive; or the amount of the blood cell particles to be tested is so large that the pattern is sometimes judged as a pseudonegative pattern instead of positive pattern.
Therefore, an operator who operates a particle pattern analyzing apparatus have to correct the judgement result of agglutination reaction. That is to say, the operator firstly has to guess the amount of the blood cell particles delivered in the reaction vessel and guess a proper particle pattern in accordance with the guessed amount of the blood cell particles, and then the operator corrects the judgement result of the particle pattern judged by the automatic judging apparatus. However, such correction of the judgement result is sometimes impossible: and in such a case, it is necessary to re-examine the sample blood all over again.
As stated above, according to the conventional particle pattern judging method, in case the blood cell particles to be tested cannot be delivered into the reaction vessel in an exact manner in accordance with the proper given delivering amount, the operator has to find out the mis-delivery and correct the judgement result. Accordingly, a lot of labor is necessary because the operator has to watch and confirm all of the particle patterns to be tested in a visual manner. Further to this, there is an individual difference in the operator's visual watching and confirming, and even if all of the watching and confirming is conducted by the same operator, it could not keep the judgement results constant. Furthermore, when the mis-delivery of the particles cannot be found out by the operator, there is a danger of misjudgement. The operator's guess as to the delivery amount of the particles in a visual manner has its limitation and it is difficult to exactly guess the amount of the particles delivered into the reaction vessel. Additionally, in case the operator's guess in a visual manner is impossible and the re-examination is requested, it would take a lot of labor and sometimes the re-examination could not be conducted when the amount of the particles to be tested is so small. Additionally, in a large sized analyzing apparatus, in which many specimens are processed with high speed, there is a danger that the mis-delivery of the particles cannot be found out resulting from the operator's fatigue.
It should be noted that in the particle pattern judging method with the aid of the agglutination reaction, the judgement largely depends upon a concentration of the blood cell particles, and therefore the variation of the delivery amount of the blood cell particles t be tested influences the judgement result delicately.